The present invention relates to a laser measuring system for forming a reference plane by projecting a laser beam in rotary irradiation from a laser rotary irradiation device, for receiving the laser beam by a photodetection device (light receiving device), and for measuring a position of operation or the like.
In the past, a laser rotary irradiation device has been known as a device for forming a reference plane to indicate a reference for operation in a wide range, and a photodetection device has been known as a device for receiving a laser beam and for measuring a position of the reference plane.
A laser rotary irradiation device forms a reference plane by projecting a laser beam with spot-like luminous flux in rotary irradiation. For instance, by projecting the laser beam in rotary irradiation within a horizontal plane, a horizontal reference plane can be formed. When the laser beam is projected in rotary irradiation within a vertical plane, a vertical reference plane can be formed. When the laser beam is projected in rotary irradiation within a tilted plane, a tilted reference plane can be formed.
A photodetection device has a photodetector for receiving and detecting a laser beam. Based on the laser beam detected by the photodetector, a horizontal reference position, a vertical reference position, etc. can be measured. A laser measuring system can be made up by combining the laser rotary irradiation device and the photodetection device. The laser measuring system using the reference plane formed by the laser beam is used for from the operation in wide range including civil engineering work to the operation in relatively limited space such as room interior finishing work, for example.
When civil engineering work is carried out, for instance, by using the laser measuring system as described above, ground-leveling work or the like is performed within a range of 100 m to 500 m in radius with the rotary laser beam at the center. In civil engineering work such as ground-leveling operation, the use of the reference plane is limited only to temporary use for level alignments, and the reference plane is not needed at all times. Also, in the case the work is temporarily suspended, the reference plane is not used as a matter of course.
However, in case the operation is performed for a wide range in space, when it is in a condition where the reference plane is not needed for the operation, it is troublesome and reduces working efficiency that power to the laser rotary irradiation device is turned on or off each time the condition may arise. In the situation as generally practiced up to now, if the laser rotary irradiation device is driven for once, the laser beam may be continuously projected in rotary irradiation for all day long. This is very wasteful if it is considered from the viewpoint of the efficiency in the use of the reference plane.
On the other hand, a battery is used as the power source for the laser rotary irradiation device, and there are limits in the power supply from the battery. This means that the time to use the laser measuring system may be limited. When the operation by using the laser measuring system is carried out for long time, the battery must be replaced periodically, and spare batteries are needed. Also, the operation must be interrupted during the exchange of batteries. In some cases, it is necessary to perform the setting of the reference plane again. This results in lower working efficiency.
Under the circumstances as described above, there have been strong demands to save the power when the laser measuring system is used.
JP-A-2000-356517 discloses an invention for power-saving control on the photodetection device.